Nano silica could greatly improve performance of sealant and adhesive, its mechanism is that Nano silica has water repelling property, when it is used in sealant, a silica net structure is formed, so gel flow is stopped, curing rate speeds up, bond effect is improved. The tightness and seepage-proofing are increased because of small size of Nano silica. When Nano silica is used in adhesive, the tensile and elongation are much better than those without Nano silica.